Label Points Online

This sample demonstrates use of a GeometryService to calculate the location of label points. To use the sample, click the Add New Polygon button, then click subsequent points on the map to draw a polygon. Double-click to complete the polygon. When a polygon is completed, a label point for the polygon will be calculated and shown on the map.

In the code-behind, a GeometryService is used to first simplify the polygon and then get a label point. When the label point is returned, it is added to the map.

XAML

<UserControl x:Class="ArcGISWPFSDK.LabelPoints"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:esri="http://schemas.esri.com/arcgis/client/2009">
    <Grid x:Name="LayoutRoot">

        <Grid.Resources>
            <esri:SimpleFillSymbol x:Key="DefaultPolygonSymbol" Fill="#7F0000FF" BorderBrush="Blue" BorderThickness="2" />
            <esri:PictureMarkerSymbol x:Key="DefaultRasterSymbol" OffsetX="12" OffsetY="12" Source="/Assets/Images/x-24x24.png" />
            <LinearGradientBrush x:Key="PanelGradient" EndPoint="0.5,1" StartPoint="0.5,0">
                <LinearGradientBrush.RelativeTransform>
                    <TransformGroup>
                        <ScaleTransform CenterY="0.5" CenterX="0.5"/>
                        <SkewTransform CenterY="0.5" CenterX="0.5"/>
                        <RotateTransform Angle="176" CenterY="0.5" CenterX="0.5"/>
                        <TranslateTransform/>
                    </TransformGroup>
                </LinearGradientBrush.RelativeTransform>
                <GradientStop Color="#FF145787" Offset="0.16"/>
                <GradientStop Color="#FF3D7FAC" Offset="0.502"/>
                <GradientStop Color="#FF88C5EF" Offset="0.984"/>
            </LinearGradientBrush>
        </Grid.Resources>

        <esri:Map x:Name="MyMap" Extent="-118.331,33.7,-116.75,34">
            <esri:ArcGISTiledMapServiceLayer ID="StreetMapLayer" 
                    Url="http://services.arcgisonline.com/ArcGIS/rest/services/ESRI_StreetMap_World_2D/MapServer" />
            <esri:GraphicsLayer ID="MyGraphicsLayer">
                <esri:GraphicsLayer.MapTip>
                    <Grid Background="LightYellow">
                        <StackPanel Orientation="Vertical" Margin="5">
                            <TextBlock Text="{Binding [X]}" HorizontalAlignment="Left" Foreground="Black" />
                            <TextBlock Text="{Binding [Y]}" HorizontalAlignment="Left" Foreground="Black"/>
                        </StackPanel>
                        <Border BorderBrush="Black" BorderThickness="1" />
                    </Grid>
                </esri:GraphicsLayer.MapTip>
            </esri:GraphicsLayer>
        </esri:Map>

        <Grid HorizontalAlignment="Right" VerticalAlignment="Top" Margin="0,10,10,0" >
            <Rectangle Fill="{StaticResource PanelGradient}" Stroke="Gray"  RadiusX="10" RadiusY="10" Margin="0,0,0,5" >
                <Rectangle.Effect>
                    <DropShadowEffect/>
                </Rectangle.Effect>
            </Rectangle>
            <Rectangle Fill="#FFFFFFFF" Stroke="DarkGray" RadiusX="5" RadiusY="5" Margin="10,10,10,15" />
            <StackPanel Orientation="Vertical" Margin="30,25,25,30" >
                <TextBlock x:Name="ResponseText" Text="Create a polygon by clicking on map. The calculated position of a Label Point will be displayed." 
                    Width="250" TextAlignment="Left" TextWrapping="Wrap" Foreground="Black" />
                <Button x:Name="ClearGraphicsButton" Content="Clear Polygons" 
                        Click="ClearGraphicsButton_Click" />
            </StackPanel>
        </Grid>

    </Grid>
</UserControl>

C#

using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.Geometry;
using ESRI.ArcGIS.Client.Tasks;

namespace ArcGISWPFSDK
{
    public partial class LabelPoints : UserControl
    {
        private Draw MyDrawObject;
        private GeometryService geometryService;
        private GraphicsLayer graphicsLayer;

        public LabelPoints()
        {
            InitializeComponent();

            MyDrawObject = new Draw(MyMap)
            {
                FillSymbol = LayoutRoot.Resources["DefaultPolygonSymbol"] as ESRI.ArcGIS.Client.Symbols.FillSymbol,
                DrawMode = DrawMode.Polygon,
                IsEnabled = true
            };

            MyDrawObject.DrawComplete += MyDrawObject_DrawComplete;
            geometryService = new GeometryService("http://tasks.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer");
            geometryService.SimplifyCompleted += GeometryService_SimplifyCompleted;
            geometryService.LabelPointsCompleted += GeometryService_LabelPointsCompleted;
            geometryService.Failed += GeometryService_Failed;

            graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;
        }

        private void ClearGraphicsButton_Click(object sender, RoutedEventArgs e)
        {
            graphicsLayer.ClearGraphics();
        }

        private void AddPolygonButton_Click(object sender, RoutedEventArgs e)
        {
            MyDrawObject.IsEnabled = true; ;
        }

        private void MyDrawObject_DrawComplete(object sender, ESRI.ArcGIS.Client.DrawEventArgs args)
        {
            MyDrawObject.IsEnabled = false;

            ESRI.ArcGIS.Client.Geometry.Polygon polygon = args.Geometry as ESRI.ArcGIS.Client.Geometry.Polygon;
            polygon.SpatialReference = new SpatialReference(4326);
            Graphic graphic = new Graphic()
            {
                Symbol = LayoutRoot.Resources["DefaultPolygonSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol,
                Geometry = polygon
            };
            graphic.Attributes.Add("X", "Label Point Polygon");
            graphicsLayer.Graphics.Add(graphic);

            List<Graphic> graphicsList = new List<Graphic>();
            graphicsList.Add(graphic);

            geometryService.SimplifyAsync(graphicsList);

        }

        void GeometryService_SimplifyCompleted(object sender, GraphicsEventArgs e)
        {
            geometryService.LabelPointsAsync(e.Results);
        }

        private void GeometryService_LabelPointsCompleted(object sender, GraphicsEventArgs args)
        {
            foreach (Graphic graphic in args.Results)
            {
                graphic.Symbol = LayoutRoot.Resources["DefaultRasterSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol;
                MapPoint mapPoint = graphic.Geometry as MapPoint;
                graphic.Attributes.Add("X", mapPoint.X);
                graphic.Attributes.Add("Y", mapPoint.Y);
                graphicsLayer.Graphics.Add(graphic);
            }
            MyDrawObject.IsEnabled = true;
        }

        private void GeometryService_Failed(object sender, TaskFailedEventArgs e)
        {
            MessageBox.Show("Geometry Service error: " + e.Error);
            MyDrawObject.IsEnabled = true;
        }
    }
}

VB.NET

Imports System.Collections.Generic
Imports System.Windows
Imports System.Windows.Controls
Imports ESRI.ArcGIS.Client
Imports ESRI.ArcGIS.Client.Geometry
Imports ESRI.ArcGIS.Client.Tasks

Namespace ArcGISWPFSDK
    Partial Public Class LabelPoints
        Inherits UserControl
        Private MyDrawObject As Draw
        Private geometryService As GeometryService
        Private graphicsLayer As GraphicsLayer

        Public Sub New()
            InitializeComponent()

            MyDrawObject = New Draw(MyMap) With { _
             .FillSymbol = TryCast(LayoutRoot.Resources("DefaultPolygonSymbol"), ESRI.ArcGIS.Client.Symbols.FillSymbol), _
             .DrawMode = DrawMode.Polygon, _
             .IsEnabled = True _
            }

            AddHandler MyDrawObject.DrawComplete, AddressOf MyDrawObject_DrawComplete
            geometryService = New GeometryService("http://tasks.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer")
            AddHandler geometryService.SimplifyCompleted, AddressOf GeometryService_SimplifyCompleted
            AddHandler geometryService.LabelPointsCompleted, AddressOf GeometryService_LabelPointsCompleted
            AddHandler geometryService.Failed, AddressOf GeometryService_Failed

            graphicsLayer = TryCast(MyMap.Layers("MyGraphicsLayer"), GraphicsLayer)
        End Sub

        Private Sub ClearGraphicsButton_Click(sender As Object, e As RoutedEventArgs)
            graphicsLayer.ClearGraphics()
        End Sub

        Private Sub AddPolygonButton_Click(sender As Object, e As RoutedEventArgs)
            MyDrawObject.IsEnabled = True


        End Sub

        Private Sub MyDrawObject_DrawComplete(sender As Object, args As ESRI.ArcGIS.Client.DrawEventArgs)
            MyDrawObject.IsEnabled = False

            Dim polygon As ESRI.ArcGIS.Client.Geometry.Polygon = TryCast(args.Geometry, ESRI.ArcGIS.Client.Geometry.Polygon)
            polygon.SpatialReference = New SpatialReference(4326)
            Dim graphic As New Graphic() With { _
             .Symbol = TryCast(LayoutRoot.Resources("DefaultPolygonSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol), _
             .Geometry = polygon _
            }
            graphic.Attributes.Add("X", "Label Point Polygon")
            graphicsLayer.Graphics.Add(graphic)

            Dim graphicsList As New List(Of Graphic)()
            graphicsList.Add(graphic)

            geometryService.SimplifyAsync(graphicsList)

        End Sub

        Private Sub GeometryService_SimplifyCompleted(sender As Object, e As GraphicsEventArgs)
            geometryService.LabelPointsAsync(e.Results)
        End Sub

        Private Sub GeometryService_LabelPointsCompleted(sender As Object, args As GraphicsEventArgs)
            For Each graphic As Graphic In args.Results
                graphic.Symbol = TryCast(LayoutRoot.Resources("DefaultRasterSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
                Dim mapPoint As MapPoint = TryCast(graphic.Geometry, MapPoint)
                graphic.Attributes.Add("X", mapPoint.X)
                graphic.Attributes.Add("Y", mapPoint.Y)
                graphicsLayer.Graphics.Add(graphic)
            Next
            MyDrawObject.IsEnabled = True
        End Sub

        Private Sub GeometryService_Failed(sender As Object, e As TaskFailedEventArgs)
            MessageBox.Show("Geometry Service error: " & Convert.ToString(e.[Error]))
            MyDrawObject.IsEnabled = True
        End Sub
    End Class
End Namespace